FIGS. 7 and 8 show a conventional exhaust system including a close-coupled catalytic converter.
A catalytic converter 52 is connected at its upstream end to an exhaust manifold 51 by an inlet connector 53 and at its downstream end to an exhaust pipe 56 by an outlet connector 54.
The inlet connector 53 is coupled at its first end to a mixing pipe 55 extending from the exhaust manifold 51 and at its second end to an inlet of the converter 52.
The outlet connector 54 is coupled at its one end to the exhaust pipe 56 and at its other end to the catalytic converter 52. The outlet connector 54 is bent at about 80 degrees with respect to a central axis C of the catalytic converter 52. In addition, the bent portion of the outlet connector 54 is designed such that a central axis D thereof intersects the central axis C of the catalytic converter 52 to increase the degree of free layout of an engine.
However, in the above described conventional exhaust system, since the diameter is of the outlet connector 54 at a portion of the same connected to the exhaust pipe 56 abruptly decreases for suitable connection with the exhaust pipe 56, pressure passing through the catalytic converter 52 is rapidly reduced at the portion where the diameter of the outlet connector 54 is reduced. This deteriorates overall engine performance since backpressure is increased.